The goal of this research is to elucidate the changes in body size, composition, and configuration occurring in adolescence, because these are important precursors of change in blood pressure and blood lipids. Hypotheses to be tested concern: (1) the time patterns of change in several indicators of body size, composition and configuration over the period of observation; (2)the relations between the time patterns of change in these indicators and the corresponding patterns for change in selected endocrine factors; and (3) the explanatory contributions of energy intake and expenditure to variation between individuals in their observed time patterns of change in these indicators. The anthropometric indicators to be addressed are: weight (total mass), height, body mass index (BMI, wt/ht2), fat-free mass, fat mass, per cent body fat, and fat distribution (waist/hip ratio). Each of these indicators will be examined first separately and then in relation to selected endocrinologic measures (testosterone, estradiol, and DHEAS) and to energy intake and expenditure (from interview histories of diet and physical activity). Existing data from up to twelve 4-monthly examinations over the age range from 8-17 years conducted in Project HeartBeat! will be analyzed. Project HeartBeat! was uniquely designed to investigate the course of change in CVD risk factors and several categories of covariates, including the anthropometric indicators addressed in this proposal. The data pertain to the 678 participants who entered the Project in 1991-93 at ages 8, 11 or 14 years of age, of whom 49.1% were female and 20.1% were black. of the 395 participants who became eligible for 10 or more 4-monthly examinations, 349 (88.4%) completed at least 10 occasions; 538 participants of 556 who were eligible for 7 or more examinations (96.8%) completed at least 7. Multi-level (MLn) analytic methods previously tested with other Project data will be utilized for this analysis. The data set is in electronic format and is immediately accessible to the Principal Investigator. The results will demonstrate the dynamics of change in these fundamental measures of body size, composition and configuration, identify their relationships with major hormonal and behavioral factors, and contribute to improvements in intervention strategies aimed at modification of blood pressure and blood lipids.